A line drive back through the middle on June 13 struck Parker on his right wrist and caused some anxious moments for him and the organization.

"I could have sworn it was broken," Parker said. "My parents were there, and they were freaking out. We went and got X-rays that night and then it was a Saturday so we had to wait until Monday to get an MRI. Luckily it wasn't and I was able to pick up where I left off."

And that was enough for the Arizona Diamondbacks' righty prospect to get selected to participate in Sunday's XM All-Star Futures Game at Busch Stadium.

As he sat in front of his locker in the United States team clubhouse, Parker was just trying to take it all in. Not only was he sitting in the Cardinals' home digs, but he was also sitting in the same spot where one day later the best the National League has to offer would be sitting.

There was a Nike representative who came by to make sure Parker had all the shoes and apparel he needed.

Not a bad spot for a 20-year-old to be in.

"It's a great honor that the Diamondbacks feel highly about me and they gave me a chance to be here and represent them," Parker said.

The D-backs have long thought highly of Parker, whom they selected with their first pick (ninth overall) in the 2007 First-Year Player Draft. Signed just before the deadline that year, Parker's innings were limited to instructional league.

In 2008, the D-backs invited him to Spring Training and he spent the season pitching for Class A South Bend, where he was 12-5 with a 3.44 ERA in 24 starts. Still, the team treated him with kid gloves and had him rely mainly on his mid-90s fastball.

This year, he's using all his pitches, mixing in a slider, curve and change.

"Now I'm free to do whatever so I just try to go out there and give my team a chance to win and compete as hard as I can," Parker said.

Parker continues to mature physically as well and has noticed a big difference in that regard this year.

"Last year at this point going into the All-Star break I was pretty tired. My shoulder was sore," he said. "Now I feel like I'm just coming out of Spring Training, just really good. I'm trying to stick with the same program and be consistent with it."

After starting the year at Class A Visalia and dominating with a 0.95 ERA in four starts, he quickly moved on to Double-A Mobile. So far with the BayBears, he is 4-4 with a 2.98 ERA.

"The lineup's obviously deeper. You can't make as many mistakes, and you pay for the ones that you do," he said. "You have to approach the hitters differently, otherwise guys will sit on your fastball. I'm learning, trying to build off every start and stay as consistent as I can with my body. I've shaped my slider a little differently. You have throw three or four pitches for a strike in Double-A, so I'm just trying to get more consistent with my offspeed stuff and keeping my fastball down rather than just getting ahead with it."

Parker's success has spurred talk of a late-season callup to the big leagues, though the D-backs seem intent on having him spend the full season in the Minors. He should however compete for a spot in the big league rotation next spring.

With that in mind, the team could send him to the Fall League if he does not reach the 150 innings they have targeted him for this year.

"I try not to think about it," Parker said about the future. "I just look forward to each start."

After a four-hour rain delay Sunday, Parker did get to see some action. With a runner on first and two out in the fifth, Parker was called on to face third baseman Alex Liddi. After falling behind, 2-1, Parker threw a 96-mph fastball to get Liddi to hit a shallow fly to right to end the inning.

Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.